24 



BULLETIN 278, U. S. DEPARTMENT OP AGRICULTURE. 



The homemade arsenate of calcium products, as noted previously, 

 were low in arsenic oxid content, but as a whole proved relatively 

 effective as poisoning agents. Formula (2), arsenic oxid 6. 16 per 

 cent, at the rate of 4 to 50, required 14 days, which was the same 

 length of time required by formula (3), arsenic oxid 3.93 per cent, 

 4 to 50, combined with lime-sulphur solution. The arsenate of cal- 

 cium prepared along with self-boiled lime-sulphur killed all larvae in 

 10 days. The experiment was closed at the end of 36 days, only 

 one larva of the unsprayed lot having died. 



Experiment XIV. 



ARSENATE OP CALCIUM VERSUS ARSENATE OP LEAD, ALONE. AND COMBINED WITH 

 LIME-SULPHUR SOLUTION, AGAINST LARV.E OP THE PALL WEBWORM. 



Homemade arsenate of calcium was again tested in comparison 

 with commercial arsenate of calcium (paste and powder) and arse- 

 nate of lead, paste. These arsenicals were used alone and combined 

 with lime-sulphur solution, 1| to 50. The results of this experiment 

 will be found in Table XIV. " 



Table XIV. — Tests of the hilling effect of various materials on the fall webwomn. 

 [Experiment started Aug. 27, 1914, Benton Harbor, Mich.; 10 larvae in each lot.] 





Name and dilution. 



Dates of examination and number 

 of larvae dying in each lot. 



Total 

 num- 

 ber 

 dead. 



Num- 

 ber 

 days re- 

 quired 

 to kill. 



Square 



inches 



foliage 



con- 



Lot 



No. 



Aug. 

 31. 







September 







2 



5 



8 



10 



14 



16 



19 





1 







 





 

 

 1 





 





 





 





 



1 

 





 





 





 





 

 







1 



1 





 



1 





 

 2 



1 

 





 







1 







1 







1 





 





 





 



3 

 

 3 



1 

 



1 



6 

 9 



6 

 7 

 8 

 5 



5 

 3 





 



3 

 1 





 2 



3 

 4 





 



4 

 2 





 





 3 

 2 



3 

 

 



4 

 1 



2 

 2 

 2 



2 



4 

 4 





 



4 



6 



7 

 



2 

 5 





 



4 



4 





 



1 

 3 



1 

 2 

 



I 











10 

 10 



10 

 10 

 10 

 10 



10 

 10 



4 

 6 



10 

 10 



10 

 10 



10 

 10 



3 

 5 



10 

 10 



3 

 



10 

 10 

 10 



10 



1 



5 



12 

 12 



14 

 14 

 12 

 12 



12 

 14 



14 

 14 



14 

 18 



14 



12 



18 



20 



18 

 14 

 20 

 14 



3.00 



? 



do 











3.00 



3 



Arsenate of lead paste, 3-50+ lime-sul- 

 phur, 1J-50 



1 



1 









2.25 



4 











.25 



fi 











2.50 



6 



do 











3.50 



7 



Arsenate of lead paste, 5-50+lime-sul- 

 phur, H-50 











.50 



8 



do 



3 







4 



3 



2 



3 

 3 



4 









1.50 



9 



Arsenate of calcium, commercial paste, 

 5-50 



3 

 1 





 1 



1 

 



63.00 



10 



do 



38.00 



11 



Arsenate of calcium, commercial paste, 



13.50 



1?, 











3.75 



13 



Arsenate of calcium, commercial pow- 

 der, 2J-50 









10.50 



14 



do 



4 







20.05 



15 



Arsenate of calcium, commercial pow- 

 der, 2J-50+lime-sulphur, 1 J-50 



do 







4.00 



If. 









1.75 



17 



Arsenate of calcium (homemade paste, 



2 

 3 





 3 



1 

 





 4 

 3 

 4 

 

 2 



1 

 



2 







1 

 



6 





 





 2 



42.00 



18 



do 



27.50 



19 



Arsenate of calcium (homemade paste, 



formula 1), 5-50+lime-sulphur, 1J-50. . 



do 



9.25 



9,0 



1 

 1 









 



10.00 



21 



Arsenate of calcium (homemade paste, 

 formula 3), 5-50 



63 00 



?? 



do 



72.25 



23 



Arsenate of calcium (homemade paste, 

 formula 3), 5-50+lime-sulphur, l£-50. 



19.50 



n 







17.00 



25 









1 





8.00 



26 



do 



1.25 



27 















 







n 



81. 00 



?,H 



do 



69.25 













